What is the treatment for a patient diagnosed with pulmonary embolism (PE) on a computed tomography (CT) scan?

Treatment of CT-Confirmed Pulmonary Embolism

Initiate therapeutic anticoagulation immediately upon CT confirmation of PE, preferably with a direct oral anticoagulant (DOAC) such as rivaroxaban or apixaban, unless the patient has hemodynamic instability requiring thrombolysis or specific contraindications. 1

Immediate Anticoagulation Strategy

The cornerstone of PE treatment is prompt anticoagulation, which should begin as soon as PE is confirmed on CT scan. The choice of anticoagulant depends primarily on hemodynamic stability and risk stratification.

First-Line Anticoagulation Options

For hemodynamically stable patients (the majority):

• Direct Oral Anticoagulants (DOACs) are preferred over traditional vitamin K antagonist (warfarin) therapy 2, 1
• Rivaroxaban is FDA-approved for PE treatment and can be started immediately at 15 mg twice daily for 21 days, then 20 mg once daily, taken with food 3
• Apixaban is FDA-approved for PE treatment and can be started at 10 mg twice daily for 7 days, then 5 mg twice daily 4
• Low Molecular Weight Heparin (LMWH) is equally effective and easier to use than unfractionated heparin for stable PE 1, 5, 6

For hemodynamically unstable patients (high-risk/massive PE):

• Unfractionated heparin (UFH) should be used initially as an intravenous bolus of 5,000 units followed by continuous infusion at 1,250 units/hour, adjusted to maintain aPTT 2-2.5 times baseline 6, 1
• UFH is preferred because it allows rapid reversal if needed and is appropriate for patients with severe renal impairment (CrCl <30 mL/min) 1

Risk Stratification Determines Treatment Intensity

After confirming PE on CT, immediate risk stratification is essential to guide treatment intensity 2:

High-Risk (Massive) PE with Hemodynamic Instability

• Systemic thrombolysis is first-line treatment with alteplase 50 mg bolus recommended 1, 7
• Bedside echocardiography showing RV dysfunction in an unstable patient is sufficient to prompt immediate reperfusion without further testing 2
• Surgical or catheter-directed embolectomy should be considered if thrombolysis is contraindicated or fails 2

Intermediate-Risk (Submassive) PE

• Routine thrombolysis is NOT recommended due to excessive bleeding risk 2, 1, 7
• Therapeutic anticoagulation alone is adequate 2, 1
• Patients with both RV dysfunction on imaging AND elevated cardiac biomarkers (troponin or BNP >100 pg/mL) should be monitored closely for early hemodynamic decompensation 2, 7
• Have a contingency plan ready for rescue reperfusion if clinical deterioration occurs 2

Low-Risk PE

• Therapeutic anticoagulation is sufficient 1
• Outpatient management may be considered for stable patients 1

Duration of Anticoagulation

Minimum treatment duration is 3 months for all patients 2, 1:

• For provoked PE (temporary risk factor such as surgery, trauma, immobilization): discontinue anticoagulation after 3 months 2, 1
• For unprovoked PE or persistent risk factors: strongly consider extended anticoagulation beyond 3 months 2, 1, 7
• Re-evaluate at 3-6 months to assess benefits versus bleeding risks of continued therapy 2, 1

Special Populations Requiring Modified Approach

Cancer Patients

• LMWH is preferred over DOACs or warfarin 1

Severe Renal Impairment (CrCl <30 mL/min)

• Use unfractionated heparin initially 1
• Transition to warfarin (target INR 2.0-3.0) for long-term therapy 1
• Avoid rivaroxaban if CrCl <15 mL/min 3

Pregnant Patients

• Therapeutic-dose LMWH based on early pregnancy weight is recommended 1
• DOACs and warfarin are contraindicated 1

Critical Pitfalls to Avoid

Do not delay anticoagulation while awaiting imaging if clinical probability is intermediate or high 2, 1. Start anticoagulation immediately unless the patient has active bleeding or absolute contraindications 2.

Do not use thrombolysis as first-line treatment in non-massive PE. The International Cooperative Pulmonary Embolism Registry found a 3.0% rate of intracranial hemorrhage with thrombolytic therapy, which is unacceptably high for patients without hemodynamic instability 8.

Do not assume subsegmental PE is always clinically insignificant. Discuss findings with radiology to confirm the diagnosis, as false-positive findings are common 2. However, if confirmed, most require anticoagulation 2.

Do not forget to assess for right ventricular dysfunction. The presence of RV strain on echocardiography or CT, combined with elevated troponin, identifies intermediate-high-risk patients who require closer monitoring despite being hemodynamically stable 2, 7.

Transition to Oral Anticoagulation

When using UFH or LMWH with planned transition to warfarin:

• Overlap parenteral anticoagulation with warfarin for at least 5 days 1
• Continue overlap until INR is 2.0-3.0 for 2 consecutive days 1

When using dabigatran or edoxaban:

• A minimum of 5 days of parenteral anticoagulation is required before switching 2, 1

Rivaroxaban and apixaban can be started immediately without parenteral lead-in, though higher initial doses must be used as specified above 2.

Follow-Up Care

Routine re-evaluation at 3-6 months after acute PE is mandatory to assess for post-PE complications including chronic thromboembolic pulmonary hypertension 2, 1, 7. This follow-up should not be omitted, as the case fatality rate of recurrent VTE in patients with prior PE is twice as high as after DVT alone 7.